The telecommunication network is required that the communication device is able to provide high reliable and uninterrupted service, and thus methods of redundancy backup and load sharing are generally used to enhance reliability of devices in a communication system. Redundancy backup refers to use a plurality of devices with the same function to carry out the switchover working, and particularly in the case of the active device being faulted or maintenance update being required, the standby device replaces the active device to continue the working, thereby ensuring the uninterrupted operation of the communication system. The load sharing is also based on the similar principle, and utilizes switchover working or co-operations of a plurality of devices to improve the system reliability.
The component using the redundancy backup should provide the active and standby switching mechanism so as to implement the requirement of the reliability and maintainability. The normal redundancy backup and active and standby switching techniques include following modes: 1+1, 1:1, and 1:N and so on, wherein the 1+1 backup refers that the active and standby units work at the same time, and the active unit is responsible for the normal working, and the standby unit should keep the consistency between various function modules and the active unit; when the abnormal case occurs and the switching is triggered, the standby unit replaces all the workings of the original active unit. For the 1:1 and 1:N backup, the standby unit only starts to work after a fault of the active unit occurs.
Generally, one complex telecommunication device comprises a plurality of processing units, and these units should work cooperatively, and therefore, various units should communicate with each other, and the connection relationships between each other are more complicated and various. And the board using the active and standby protection generally has more connection relationships with other boards, and its status is very important. Therefore, the protection switching mechanism certainly should have very high reliability so as to minimize the damage to the services in the switching process. The switching is usually divided into different varieties such as the manual switching, automatic switching, and compulsory switching and so on according to different causes of triggering the switching. The present invention does not pay attention to the causes of the switching.
At present, there are many protection switching methods for the active and standby function units with the single function, and FIG. 1 shows a typical structure of the system for switching the active and standby boards, and the system comprises: an active board and a standby board, wherein the active board comprises: an active function unit, an active control unit and an interconnection signal interface, and the standby board comprises: a standby function unit, a standby control unit and an interconnection signal interface. However, the complexity of the current telecommunication devices becomes higher and higher, and sometimes, the system designer will integrate a plurality of function units separated from each other into one board based on a certain concern. Then the requirement of the active and standby switching of this board will be higher than the active and standby switching which only has the single active function unit and single standby function unit.
For a system for switching the active and standby boards comprising multiple function units, if requirements of these function units for the active and standby states are the same, for example all of them are required to avoid being in the active state at the same time, but can be in the standby state at the same time in a short term, then the problem is not serious, and it can be required that all the function units of the active board are switched to the standby state at first, and then the standby board is notified to switch all the units into the active state. However, if requirements of these function units for the active and standby states are different in the switching process, the case is completely different. For example, the function units A on the active and standby boards are required to be unable to have the time of being in the active state occurring at the same time, otherwise the service interruption will be caused; however, the function units A on the active and standby boards are able to be in the standby state in a short term at the same time. For example the Ethernet function units, if the active state occurs at the same time, a serious consequence of forming a ring is caused. At present, a majority of function units belong to this case. However, the function units B are required to be unable to have the time of being in the standby state occurring at the same time, otherwise the service damage will also be caused; however the function units B are able to be in the active state in a short term at the same time; for example for the active and standby clock units, the standby clock unit wants to extract the clock of the active clock unit, thereby synchronizing to the active clock unit; if both are in the standby state, then both will extract the clock from the other, which will cause a serious consequence of the clock losing lock. If the requirement of the system design is to integrate the function units A and B into one board and the system is also required to be able to securely implement the active and standby switching, and the traditional switching way attends to one thing and loses the sight of another, and is obviously unable to satisfy the requirement. For the more complex system, for example the system comprises a plurality of function units which are required to avoid being in the active state at the same time and a plurality of function units which are required to avoid being in the standby state at the same time, the prior art is unable to implement the active and standby switching.